Device for conducting current to a rotating electroplating barrel

ABSTRACT

An arrangement for conducting electrical current to the interior of a rotating drum for the treatment of surfaces on articles within the drum. Electroplating current is conducted from a stationary source to the bearings of a rotating drum, by way of a flexible cable. A flexible shaft made of a series of interlinking elements, carries a conducting cable having one end secured to an assembly rotating with the shaft. The rotating assembly envelops a stationary disc-shaped member through which current is conducted to the movable assembly and the cable secured thereto.

March 19, 1974 D 3,798,148

CURRENT TO A ROTATING DEVICE FOR CON CT ELECTRO TING BARREL Filed Aug. 25, 1972 1 2 FIGJ United States Patent O I 13 Claims ABSTRACT OF THE DISCLOSURE An arrangement for conducting electrical current to the interior of a rotating drum for the treatment of surfaces on articles within the drum. Electroplating current is conducted from a stationary source to the bearings, of a rotating drum, by way of a flexible cable. A flexible shaft made of a series of interlinking elements, carries a @011 ducting cable having one end secured to an assembly rotating with the shaft. The rotating assembly envelops a stationary disc-shaped member through which current is conducted to the movable assembly and the cable secured thereto.

BACKGROUND OF THE INVENTION The present application is a continuation-in-part application of the parent application Ser. No. 75,164, filed Sept. 24, 1970, and now abandoned.

Electroplating drums as known in the art, consist primarily of plastics, and are preferably in the form of horizontally rotating drums having, for example, a hexagonal cross-section. The walls of the drums are perforated, and one side face of the drum shell is designed as an opening which can be closed with a cover. The loading and unloading of the drums with parts or articles to be electroplated, is accomplished through closable opening means. The shell of the drum is closed at both sides by polygonal end faces which are perpendicular to the axis of symmetry and rotation. The bearings which retain the rotating drums, are arranged on the end faces of the drum.

Drums that rotate in hollow bearings are known in the. art. In such drums, a chemically and electrically insulated flexible cable is introduced through the hollow openings of the bearings, and the flexible cable extends into the interior of the drum which ends in a so-called contact pair.

This conventional design as known in the art; however, has the disadvantage that the cable surrounding the object or article to be electroplated, breaks frequently during the continuous rotation of the drum. This breakage results from the constant and continuous back-and-forth twisting of the cable.

Another disadvantage of the conventional design is that the conventional devices cannot always be used in drums with strip or buttton contacts as they are knownin the art, or in drums with central anodes. This results from the condition that the electroplating current must be conducted over structural elements which slide against each other at least at the transition point.

In order to overcome the preceding disadvantages it has been suggested in the German Pat. No. 1,192,490, to provide for the support of a bearing pin on each of the two supporting arms, a blind bearing bushing of metal mounted on the end faces of the drum. This blind bearing bushing is inserted'in a plastic lining bushing secured in the hub hole of the drum, and a plastic flexible hose surrounds the supporting arm concentrically beyond the back level adjoining the lining bushing, liquid-tight. This 3,798,148 Patented Mar. 19, 1974 plastic hose rotates with the drum about the supporting arm.

It was found in practice, however, that the flexible plastic hoses which are designed as relatively thin-walled siphontubes, have only a relatively short life, due to alternating elongations and contractionsof the bases. The production or fabrication of the siphons is, furthermore complicated, and their operation is unreliable since hairlike cracks in the walls thereof are mostly discovered too late, and the attacking bath solution escaping through the siphon wall has then sufficient time to corrode the metal parts on the drum hearing. The replacement of a siphon, furthermore, is time consuming, and requires disassembly of the drum from the electroplating plant.

The central conduction of the electroplating current to the end faces of the drum, moreover, is achieved through flexible cables. The ends of the cables associated with the end faces are rigidly fixed to the latter, and follow the rotation of the drum in synchronism. The second end of the cables rotate in a bearing bushing outside of the electrolyte.

A substantial disadvantage of the preceding embodiment results from the condition that the mechanical loads of tension and pressure on the periphery of the copper cables, due to the constant rotation of the cables, lead to cable breakage within a relatively short time of operation. Furthermore, there are upper limits for the surface and cross-section of the rotating cables, so that high electroplating currents are not permitted.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the disadvantages enumerated above with regard to the conventional devices and designs known in the art.

Another object of the present invention is to provide an arrangement for conducting electroplating current to a. rotatingd'rum, which is highly reliable in operation, and requires substantially little maintenance.

A further object of the present invention is to provide an arrangement as set forth, which has a substantially long operating life.

A still further object of the present invention is to provide an arrangement of the foregoing character which is simple in design, and may be economically fabricated and assembled.

The objects of the present invention are achieved by providing that the current-carrying cables for conducting the electroplating current to the bearings of the drum, are arranged separate from a flexible shaft which rotates synchronously with the cables.

According to the present invention the current conduction takes place preferably above the level of the electrolyte. The cables, thereby, conduct the electroplating current from the transfer point-the point at which the current transfers from stationary to movable parts, to the drum bearing independent of the rotating flexible shaft which serves merely as a support and as a guide for the cables which carry the current. This flexible shaft also serves as a means for transmitting the mechanical motion of rotation'from the drum to the transfer point. The arrangement of the cables, in accordance with the present invention, furthermore, is such that their axes of symmetry do not coincide with the axis of the shaft. The length of the cables, morover, are preferably greater than the strength of the associated flexible shaft.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best' understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAW'ING FIG. 1 is a side view and shows a galvanizing drum provided with the arrangement for conducting electroplating current to the drum, in accordance with the present invention; and e FIG. 2 is a sectional view of two associated normal elevations for the design of a link used to form the flexible shaft in the arrangement of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS not shown. Thus, the gear on the drum end 2 is linked to a driving source which causes the rotation of the drum. The direction of rotation of the drum 1 is indicated by the symbol n (r.p.m.) in the drawing, and this symbol shows the drum to be rotating counterclockwise. Bearing shaft members 4 and 5 are fixed to the drum and rotate within fixed or stationary bearing arms 6 and 7, respectively. These bearing arms 6 and 7 also serve to support the drum while rotating with its bearing shaft portions 4 and 5.

The flexible shaft 8 which rotates with the drum, is assembled with a suitable number of prefabricated identical links 9 which interlock in the manner of a chain lock and form pairs of couplings that are flexible in' an axial direction. The chain of links 9 constitutes the flexible shaft 8, and the bottom end of the shaft 8 is rigidly or fixed to the end face 2 of the drum at the axial center of the drum.

Drum 1 and shaft 8 both turn in the same direction and have the same speeds, n The drum 1 applies rotating torque to the shaft by transmitting torque from one link 9 to the other, so that the disc 10 at the upper end of the shaft rotates with the drum. The disc 10 is rigidly mounted or'fixed to the end of the shaft 8. The interior of the member 10 has a circular-shaped cavity to ac -v commodate a stationary disc-shaped member 12 within the cavity. On top of member 10, is a coverllwhich is secured to the member 10 and rotates with ,the member 10.

Within the Cavity recess ofthe brflo'lsia stationary disc-shaped member 12, which extends 'from a stationaryshaft portion 13. Thus, relative motion prevails between the part 12 and the member 10. The shaft ll l'af is electrically connected to the negative 'polei'o'f avdireet.

current (DC) source. This shaft 13 is also fixed or se cured to the supporting frame for the drum urri rch. also the supporting arms 6 and 7 are conrie c'te'd...-Ihus,; the stationary supporting arms 6, 7 and the ,s atm ary. shaft 13 are all connected to the supporting frame 'for the drum.

Within the cylindrical recess of the member' litlgareele-i.

ments 14 which serve to transmit electrical current bements 14 are pressed between the disc-shaped fpart'12 and the interior surface of the member 10, so that the current may be transmitted through these partswhich slide. relatively to each other. The elements 14, may, for example, be in the form of laminated contacts, as generally preferred in the trade, and may be made ofielas'tic' rnaterial having gOOd electrical Conductivity and highlthe rmal load capacity.

" Parts 10, 11,. 12," 13 and 14 constitute substantially the transfer point of the electroplating current. This transfer point of the electroplating current. This transferpoint is above the level of the electrolyte, and serves to transfer the electrical current from stationary parts to rotating parts, in accordance with the present invention. The height of the electrolyte level is indicated in FIG. 1 by the triangle designated x. The transfer point represents that point at which electrical current is transferred from mov- 10 ing parts to rotating parts/The moving or rotating parts are .represented by the members 10 and 11, Whereas the fixed or stationary parts are represented by parts 12 and 13. The contact elements 14 may be in the form of spring elements additionally, in order to assure substantially 15 good electrical contact between the moving and stationary parts.

- Links 9 which constitute the flexible shaft 8 consist sub stantially of electrically non-conductive material which is chemically and thermally resistant to electrolytes. Thus,

this material is preferably a chemically and thermally stable plastic as, for example, a'thermoor duroplast. The

links 9 made of such material can be produced or fabricated in advantageous manner by, for example, injection molding. It is also possible to fabricate the links 9 of metallic materials, however, provided that no secondary conductor effects'ari'se'o'n the links due to bipolar action.

It has been found, in accordance with the present in vention, that such a material which meets these requirements can be'derived from titanium. If another type of metallic material is used, then the latter must be insulated liquid-tight against the electrolyte by sheathing, for example, with a rotating flexible hose of electrically nonconductive material which is resistant to the electrolyte.

The parts to be electroplated are in rotating drum 1 and touch constantly a number of contact elements which are under cathodic potential. The electrical connection between the contact elements in the drum and the disc 10 is achieved, in accordance with the present invention, over one or several flexible cables 15 which are arranged substantially concentric or parallel with the shaft 8.'In

an advantageous design, the cables 15 are arranged spirially.-or helically about the shaft 8 and rotate loosely suspended about, the shaft. Cables 15 are coated liquid-tight with an electrically insulating flexible sheet made of for example,'1'a-suitable plastic which is resistant to electrolytes. Preferably, at least two independent current'carryingicables are used.

The upperyends of the cables '15 are secured to the disc 10, while the other ends of the cables are secured to the hearing shaftportion projecting from the drum face end 2.- *The connecting ends of the. cables are rigid, and thelower ends of .the cables 15 are,"additionally, liquid-tightinsulated from the electrolytesZThe insulated cable ends contact elements, generally known in the art as buttons,

or strips, provided on the drum shell, for example, or to the cathodic contact disc provided on the end faces of the drum.

In accordance with the present invention,, the-number:

of cables that may be provided is not limited, and there I fore the, magnitude of the electroplating current may be of any. amount found to be advantageous. There is, furthermore, no cooling problem due to:the formation of Joulean heat or frictional heat in thebearings, in'accordance withthe-present invention. The transfer point for the electroplating current over sliding elements, takes place "outside of the electrolyte, ,and therefore the parts. con-,-

stituting;. t heJransfer point maybe designedof whatever dimension is desired. The parts constitutingthe transfer. points need not be insulatedform the electrolyte, and ,1 sufficient-cooling isobtained through natural conduction, g so that no artificial cooling need be applied.

The Joulean heat in the individual cables is substantially low, and is eliminated through the surround bath solution. Furthermore, the mechanical bearing of the drum forms a separate group of structural elements, which does not interact with the conduction of the electroplating current to the drum bearing.

FIG. 2 shows one of the links 9 used to constitute or form the flexible shaft 8. Link 9 consists substantially of a ring-shaped center piece 16 having attached, on the top side, three carrier and guide projections or fingers 17. These projections or fingers 17 engage recesses 18 on the lower side of the adjacent link 9. The chain collection of the links 9 form the flexible shaft 8, and resembles thereby a multiple Cardan joint.

Thus, the interlinking of the element 9 to constitute the flexible shaft 8, is accomplished by the fingers or projections 17 engaging the recessed portions 18 of the adjacent links. Motion is transmitted from one link to the other, in sequence, throughout the flexible shaft, by having one link with its finger or projections 17 engage the adjacent link through its recesses 18. The links 9 are, furthermore, held together through a member passing through the central opening of these links. It is an essential object of the links 9 to serve as a guide for the cable 15 which is threaded through the openings 20 of the arms 19, that are part of the links 9. Accordingly the links 9 provide a means for maintaining the cables 15 in an orderly manner rotating with the shaft 8, and independent of this shaft 8. The cables 15 are electrcially in contact with the member and conduct current to the drum 1.

The central bore of the shaft link 9 is provided for the purpose of receiving a rigid guide element, as, for example, a curved tube of titanium which assures that the shaft 8 remains unchanged in form. By retaining the form of shaft 8, thus unchanged, the radius of curvature of this shaft is maintained. The links 9 are articulated with each other and rotate about the rigid guide element.

The central ring of the link 9 may have three supporting arms 19, for example, spreading in star form, if three flexible cables are to be used. These arms 19 terminate in eye-shaped ends 20. The flexible cables 15 are threaded through these eyes 20 and are thereby held at a substantially constant distance from the axis of rotation of the shaft.

It is another feature of the present invention that flexible shaft 8 and cables 15 are surrounded jointly by a rotating flexible hose which insulates them in a liquid-tight manner from the electrolyte. The hose is made preferably of an electrically non-conductive material which is chemically and thermally resistant to the electrolyte.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of electroplating current conduction arrangements differing from the types described above.

While the invention has been illustrated and described as embodied in electroplating current conduction arrangements, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

What is claimed is:

1. An arrangement for conducting electroplating current to an immersion electroplating drum, comprising, in combination, a rotating immersion galvanizing drum; supporting arms with bearings for supporting said rotating drum; at least one cable rotating with said drum for conducting said current to one of said bearings; a flexible shaft supporting said at least one cable and rotating synchronously with said cable and said drum, one end of said shaft and said at least one cable being connected to said one bearing; a stationary source of electrical current; and current transfer means mounted on the other end of said shaft and connected to the other end of said at least one cable, said transfer means contact-ing electrically said source of electrical current for transferring electrical current from said stationary source to said at least one rotating cable, the axis of said at least one cable being spaced from the axis of said shaft and being electrically independent of said shaft, the direction of current flow through said cable being spaced from the axis of said shaft and being substantially nonparallel with the axis of said shaft.

2. The arrangement as defined in claim 1, wherein said at least one cable has a length exceeding the length of said shaft.

3. The arrangement as defined in claim 1, including at least two independent current-carrying cables.

4. The arrangement as defined in claim 1, wherein said at least one cable is arranged substantially concentric with respect to said shaft.

5. The arrangement as defined in claim 1, wherein said at least one cable is arranged substantially spirally about said shaft.

6. The arrangement as defined in claim 1, wherein said shaft comprises a plurality of elements having supporting arms extending from the axis of said shaft and having eyeshaped ends at said arms with openings for insertion of said at least one cable therethrough, said arms and said elements of said shaft extending radially from the axis of said shaft and surrounding said shaft; and a rigid guide member passing through the centers of said elements for retaining said elements assembled in a predetermined configuration.

7. The arrangement as defined in claim 1, including a liquid-tight electrically non-conductive sheath on said at least one cable, said sheath being resistant to electrolytes.

8. The arrangement as defined in claim 1, wherein said shaft comprises a chain of prefabricated assembled link elements forming flexible couplings in radial direction, each of said links having projections and recesses for interlocking with adjacent links, said links being identical.

9. The arrangement as defined in claim 8, including a rotating flexible hose covering liquid-tight said shaft, said hose being of electrically non-conductive material resistant to electrolytes.

10. The arrangement as defined in claim 9, wherein said hose covers liquid-tight said shaft and said at least one cable.

11. The arrangement as defined in claim 8, wherein each of said links has supporting arms extending radially from the axis of said shaft and having eye-shaped ends at the ends of said supporting arms with openings for the insertion of said at least one cable therethrough.

12. The arrangement as defined in claim 11, wherein said shaft is of electrically non-conductive material resistant to electrolytes.

13. The arrangement as defined in claim 11, wherein said shaft is of titanium.

References Cited UNITED STATES PATENTS 3,152,060 10/1964 Belke 204-213 JOHN H. MACK, Primary Examiner W. I. SOLOMON, Assistant Examiner US. Cl. X.R. 204214 

